because you think one day you will be rich.
or you just try to recover loss.
Simply said. There is that thought that dont give u peace in head that u will earn something big and recover all losses. Definitley it has something with how big amounts u play. Excitement that gambling brings to us is also one of important things why is gambling so addictiv. In my casse when ever i win or lose I feel it, so cause of that I like to gamble.